Variability in drought sensitivity of upland rice varieties used in Madagascar’s Central Highlands

Abstract

In Madagascar’s Central Highlands, 70% of farmers depend on upland rice (Oryza sativa L.) for their livelihoods. However, these agrosystems are increasingly exposed to drought due to erratic climate change effects and decreasing rainfall. The objective of this study was to explore the variability in drought sensitivity of local upland rice varieties, which are characterised by low genetic diversity due to strong selection for cold tolerance and blast resistance. A greenhouse experiment was conducted, where five upland rice varieties commonly used by farmers, namely Chhomrong Dhan (the control variety), FOFIFA 173, FOFIFA 186, FOFIFA 200 and FOFIFA 201, were subjected to four soil water regimes, representing increasing levels of drought stress. These treatments included well-watered (control), rolling stage, drying stage and death stage. Results showed that under each soil water regime, none of the tested varieties differed significantly from the control variety, Chhomrong Dhan, in terms of biomass production. However, FOFIFA 186 and FOFIFA 201 exhibited a 2–3 days delay in the onset of drought stress symptoms, and survived longer. Such a delay represents a meaningful advantage in Madagascar’s Central Highlands, where consecutive dry days are frequent at the beginning of the cropping season. This response may reflect more conservative water-use strategies and/or greater physiological tolerance to drought. However, further studies are required to confirm the underlying mechanisms. These findings provide valuable insights for future research and breeding programmes aimed at improving the climate resilience of upland rice in Madagascar’s Central Highlands.